Which oil viscosity should I run?

[mrtleavitt]

Well guys, I know this is a totally opinionated question so that's what I want. I don't want any fights here, just an opinion and maybe a quick explanation. I got my 428 going the other day and had the oil passages drilled out for more flow. I am currently running 10w-30 oil and my oil pressure is good at idle but once the engine has ran for 10 minutes or so the pressure drops. This engine is in a street truck, Edelbrock heads, roller cam, so I have a high reving performance engine, I was debating on going to a thicker oil like 10w-40 or maybe even 20w-50 but what do you guys think? I live in Utah but the truck is parked all winter. When school gets done I will return home to Las Vegas so usually the temperature outside will be between 50 and 120 degrees F. Thanks for the input guys

[70_F100]

10W-30 should be just fine.

Low pressure at idle is not a problem.

I put 10W-30 in hundreds of heavy-duty diesel engines during my career, and I'm not aware of any oil-related failures because of the viscosity.

[427]

My 427 when it gets hot the pressure drops to idle at 15psi. As soon as the rpm comes up it shoots up quick. I run 20w50 Havoline here in east TN with no problems.

[fordman]

10w 30 for summer time. witner time 10w 40

[70_F100]

Fordman, you've got that backwards.

If you're going to run thicker oil, it needs to be when the weather is hotter, not colder.

Actually, all of the auto manufacturers pretty much specify the same viscosity oil year-round, unless you're in a climate that's REALLY cold or REALLY hot.

[fordman]

your right i did get that backwards oops.

[JEF199]

I know most like 20w-50 just because its thicker. I personlly run Rotella 15w-40. But I would like see if anyone with a manual or a memory.....What did ford recomend?

[fordman]

from the dip stick. "warranty requires M2C33-F oil" i didnt open my factory manual. but 70_f100 did .

[JEF199]

"M2C33-F" thats atf isn't?

[BobbyFord]

Factory manual says:
10-90 degrees F.....10W30
10-90+ degrees F....10W40

[fordman]

"M2C33-F" thats atf isn't?

your right i was looking at a stupid trans dip stick.

[ToughOldFord]

I use 15-40, but I don't get the sub-zero temps some of you guys do.

[BobbyFord]

Also, the oil recommendations in the shop manual were printed in 1972 when our trucks were new and set to factory tolerances. Therefore I think they are merely guidelines. None of our trucks are still at factory tolerances. When rebuilding an engine, lower end clearances will vary depending on the oil viscosity that the engine owner intends to use.

[fordman]

that is a very good point.

[cdeal28078]

I broke my cam in with Rottella 15W50 and stuck with it. I did go to the 115W40 last oil change though. I once tried the 10W30 and I just did not like the way the oil pressure bounced at idle. I know it wasn't hurting anything though. I run about 75 pounds cold idle, 70 or so hot and cruising 25 or so hot idle. My bearings were on the closer side though.
Rottella had more Zinc in it when I did my cam swap which is why I stuck with it. I have since read where it doesn't anymore though.
clint